Cooling systems for electron discharge tubes



June 18, 1968 c N. O'LOUGHLIN 3,388,740

COOLING SYSTEMS FOR ELECTRON DISCHARGE TUBES Filed Nov. 21, 1966 2 Sheets-Sheet l AT TORNEYS COOLING SYSTEMS FOR ELECTRON DISCHARGE TUBES June 18, 1968 c, N. O'LOUGHLIN 2 Sheets-Sheet 2 Filed Nov.

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ATTORNEYS United States Patent 3,388,740 COULTNG SYSTEMS FUR ELETRON DISCHARGE TUBES Clan Noel GLoughlin, Essex, England, assignor to English Electric Valve Company Limited, London, England, a British company Filed Nov. 21, 1966, Ser. No. 595,669 Claims priority, application Great Britain, Nov. 24, 1965, 50,004/65 '7 Claims. (Cl. 165-495) ABSTRAQT OF THE DTSCILQSURE An electron discharge tube cooling system including a boiler into which is inserted a portion of a discharge tube to be cooled is disclosed herein. The boiler includes a vapor outlet in communication with a condenser which returns condensed coolant to a coolant supply reservoir. Suitable fluid supply provisions are included for supplying coolant to the boiler and a boiler coolant level maintaining device is mounted externally of the boiler for maintaining a predetermined coolant level within the boiler. The coolant level maintaining device includes an internal weir having an overflow level at the level of coolant to be maintained within the boiler.

This invention relates to electron discharge tube cooling systems, and more specifically to water cooling systems for klystrons and other high power electron discharge tubes.

The invention is illustrated in and explained in connection with the accompanying drawings in which FIG- URES '1 and 2, which are provided for purposes of explanation, relate to typical known water cooling systems for electron discharge tubes and FIGURES 3, 4 and 5 illustrate the present invention.

The generally employed electron discharge tube Water cooling systems incorporating water pumps in the cooling circuits to circulate the coolant, suffer from the disadvantage that pumps usually employed do not operate efiiciently above a certain temperature, typically 80 C., and thus means must be provided to ensure that Water entering the pump is below this temperature. Such means usually take the form of one or more heat exchangers interposed in the cooling circuit between the inlet to the water pump and the outlet of the boiler, is. that part of the cooling system to which heat is transferred from the tube to be cooled. Such exchangers are both bulky and expensive.

Referring to FIGURES 1 and 2 in which FIGURE 1 represents schematically a typical known cooling system for a high power klystron tube and FIGURE 2 is a schematic cross-section of a typical known boiler arrangement of the so-called internal weir type, heat is transferred to the water in a boiler 1, in which the collector of the klystron (not shown) to be cooled is immersed. FIGURE 1 shows two separate cooling systems, one starting at the boiler 1, in which the heat from the klystron collector raises steam and the other (in which steam is not produced) starting at a water jacket 6 which is used for cooling the body of the klystron.

The boiler 1 is fed with water from a water reservoir 2 by a pump 3, the water level in the boiler being maintained at a desired substantially constant level sumcient to immerse the collector of the klystron, by means of an internal weir shown in FIGURE 2. Steam from the boiler Cl passes to condenser 4 which produces outlet water which is typically at about 80 C. A condenser producing outlet water at such below this temperature would be undesirably costly. The outlet water has added to it, via pipe 11, the overflow, typically at a temperature "ice of about 100 C., from the internal weir in the boiler 1. The mixture of condenser outlet water and weir overflow will be at a temperature between C. and C. and is fed through a water heat exchanger 5 in order to cool it below about 80 before returning it to the reservoir 2 whence it is re-circulated by the pump 3. A second cooling system is provided for the klystron body water jacket 6 and comprises a reservoir 7, a pump 8 and a water heat exchanger 9. The operation of this second cooling system will be apparent from the figure and accordingly will not be further described. The blocks X represent the normally provided water interlocks.

FIGURE 2 shows the internal weir in the boiler 1. This includes a water inlet 10 (fed from the pump 3) and a water outlet pipe ll l, which extends upwards Within the boiler body to form a weir 12. The water level (shown by the dotted line) in the boiler is maintained at the top of the weir .12 by water supplied by the pump 3, surplus water overflowing through the pipe 11. This water will obviously be near boiling temperature.

The present invention seeks to simplify and cheapen the cooling system principally by eliminating the heat exchanger 5 while still supplying the pump 3 with water at a temperature low enough to enable it to operate elficiently.

According to this invention an electron discharge tube cooling system of the kind in which part of a tube to be cooled is immersed in coolant in a boiler which is supplied with said coolant from a reservoir, a desired predetermined level of coolant in said boiler being maintained automatically by returning to said reservoir surplus coolant which, it supplied to said boiler and not so returned, would raise the level therein above said predetermined level comprises means, external to said boiler and lay-passing the same, for returnin said surplus coolant to said reservoir whereby substantial heating of said surplus coolant by passage through said boiler is avoided.

Preferably the surplus coolant is returned to a pipe which leads from a condenser, fed from said boiler with vaporised coolant therefrom, to said reservoir.

Normally the coolant will be water but the invention is not limited to the use of this material as the coolant.

In one way of applying the invention to a cooling system in which coolant from a reservoir is supplied to the boiler by a circulating pump and vaporised coolant from the boiler is condensed by a condenser and returned to the reservoir there is provided a coolant inlet pipe admitting coolant to the boiler at a low level therein and another also admitting coolant to a weir which is external to said boiler and has an overflow level at the level desired to be maintained in the boiler, coolant overflowing said external weir being returned to said reservoir.

The external weir may be constituted by the upper end of a pipe which is fed with coolant by a branch out of an inlet pipe supplying coolant to said boiler at a low level therein and which is surrounded by a jacket which is open to atmosphere, said jacket having a, coolant outlet pipe leading from a low level therein to the reservoir. In a modification the external weir is constituted by the top of a partition extending upwards from the bottom of a container which is open to atmosphere, said container having, on one side of said partition, a coolant inlet pipe from the reservoir and a coolant output pipe supplying coolant to the boiler at a low level therein, and, one the other side of said partition a coolant outlet pipe for returning coolant from a low level in said container to the reservoir.

1 Where cooling of a second part of a discharge tube is requiredfor example where the tube is a klystron having a body cooling water jacket-the cooling member for that part (the said jacket) is preferably included in series in the water circulation path from the pump.

FIGURE 3 is a schematic cross-section of a boiler arrangement used in a system according to the invention and FIGURE 4 is a schematic representation of a cooling system embodying the invention.

Referring to FIGURE 3, the boiler proper, 1, in which the klystron collector (not shown) is situated, no longer contains the internal weir/Coolant water is supplied by the branched inlet pipe 14 which has one branch 15 entering the boiler low down and another branch 16 which is external to the boiler and has an open end at the height of the level 17 at which Water is to be maintained in the boiler. Surrounding the branch 17 and extending from just above the branch 1-5 to about the top of the boiler is a jacket 18 with the interior of which the pipe 16 communicates and which has a Water outlet pipe 19 near the bottom. The jacket 18 is open to atmosphere through a hole 20 in the top thereof. As will be seen the arrangement illustrated in FIGURE 3 includes a weir, external to the boiler, by means of which surplus water supplied by the pump is returned to the reservoir, the weir being constituted by the top of the pipe 16 at the desired level to be maintained in the water. In this way the boiler is by-passed, so far as the retained surplus water is concerned and this water is no longer heated by being passed through the boiler. Steam raised in the boiler passes out through the steam outlet pipe 21.

Since there is little or not heat transfer from the boiler 1 to the water in the inlet pipe branch 16 or to that in the jacket .18, the temperature of the coolant leaving the outlet pipe 19 will not be materially above that of the coolant entering through the inlet pipe 14.

Referring to FIGURE 4, (in which pipes are diagrammatically represented by single lines) the pump 3 supplies water from the reservoir 2 to a klystron body water jacket 6 (as in FIGURE 1), water from which enters the boiler 1 via inlet pipe 14. The pump also feeds water to the inlet pipe 14. In the case illustrated, in which there is a klystron body water jacket 6, the water from the pump 3 is fed to the pipe 14 through the klystron jacket 6 which is thus directly in series in thewatercirculation path. Steam from the steam outlet pipe 21 passes to the condenser 4 the condensed water from which circulates via the flow interlock X to the'water reservoir 2. The water outlet pipe 19 (from the jacket 18, FIG- URE 3) joins the condenser outlet pipe at a point before the water interlock and the piping from the jacket to the reservoir is finned for better cooling as indicated at 23.

In operation the klystron collector immersed in the water in the boiler 1 boils it, producing steam which passes to the condenser 4 the water from which is approximately at 80 C. This water is mixed with the overflow from pipe [19 and, owing to the relatively low temperature of this water, the mixture will be at a temperature of only about 50 to 60 C. The heat exchanger of FIG- URE 1 is thus no longer necessary. The firming 23 further assists the cooling process. The water fed to the pump 3 is thus kept at a temperature at which a normal pump will operate efliciently.

In the modification illustrated in FIGURE 5 a somewhat diiferent arrangement of external weir is used for the surplus water. In this embodiment there is an external container 181 which is open to atmosphere at the top through the hole 20. The container 181 has a traverse partition 1611 which extends up from the bottom thereof to a level which is the same as the level desired to be maintained in the boiler. Water pumped from the reservoir 2 by the pump 3 (FIG. 4) enters the container 1-31 at the bottom on one side of the partition 161 through the inlet pipe 14d and some of this water is supplied to the boiler at a low level through the pipe connecting the boiler with the container on this side of the partition. Surplus water pumped in through the pipe 141 fills this side of the container to the level of the top of the partition and overflows into the space on the other side of the partition whence it is returned to the reservoir Zvia the low level outlet pipe 19 as in FIGURE 4. In this embodiment the external weir is constituted by the top of the partition 161 the level of the top of which determines the level of water maintained in the boiler.

Where, as in the examples illustrated, there is provided cooling for the klystron body, the klystron water jacket may be, as already described, in series in the water circulation path thus eliminating the heat exchanger -9 of FIGURE 1. i

I claim:

1. An electron discharge tube cooling system of the kind in which part of a tube to be cooled is immersed in coolant in a boiler which is supplied with said coolant from a reservoir, the cooling system comprising a boiler having a vapor outlet, a condenser in communication with said vapor outlet, a reservoir and means connecting said condenser with said reservoir, boiler liquid level maintaining means external of said boiler for maintaining a predetermined coolant level in said boiler, said level maintaining means being in communication with said boiler and said reservoir for returning surplus fluid to said reservoir, and means for supplying coolant from said reservoir to said level maintaining means.

2. An electron discharge tube cooling system as claimed in claim 1 including means for returning the surplus coolant from said level maintaining means to said means connecting said condenser with said reservoir.

3. An electron discharge tube cooling system as claimed in claim 1 wherein said means for supplying coolant from said reservoir to said level maintaining means comprises a circulating pump, said means for maintaining comprising a weir external to said boiler and having an overflow level at the level desired to be maintained in the boiler, and coolant inlet pipe means for admitting coolant to the boiler at a low level therein and for admitting coolant to said weir, whereby coolant overflowing said external Weir is returned to said reservoir.

4. An electron discharge tube cooling system as claimed in claim 3 wherein said level maintaining means comprises a jacket open to atmosphere and having a coolant outlet opening at a low level therein in communication with said reservoir, and weir comprising the upper end of a pipe within said jacket and said means for admitting coolant comprising a branched inlet to said boiler at said low level thereof and to said pipe within said jacket.

5. An electron discharge tube cooling system as claimed in claim 3 wherein said level maintaining means comprises a container open to atmosphere, said weir comprising the top of a partition extending upwards from the bottom of said container, said container including a coolant inlet opening on one side of said partition and in communication with said reservoir, a coolant outlet opening in communication with said boiler at said low level thereof for supplying coolant to said boiler and a coolant outlet opening on the remaining side of said partition in communication with said reservoir for returning coolant from a low level in said container to said reservoir.

d. An electron discharge tube cooling system as claimed in claim 1 and including an additional cooling chamber for cooling a separate part of the electron discharge tube to be cooled, said additional cooling chamber being effectively in series in the coolant circulation path from and to the reservoir.

7. An electron discharge tube cooling system as claimed in claim 1 and further comprising finned piping means for cooling the coolant being returned to said reservoir.

References Cited UNITED STATES PATENTS 2,873,954 2/1959 Protze 165-74 X 2,969,957 1/ 1961 Beurtheret 165-74 X 3,280,897 10/1966 Beurtheret 165105 X ROBERT A. OLEARY, Primary Examiner. A. W. DAVIS, Assistant Examiner. 

